<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link rel="stylesheet" href="./css/index.css" />
  <title>记事本</title>
</head>

<body>

  <!-- 主体区域 -->
  <section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <input placeholder="请输入任务" class="new-todo" v-model="things" />
      <button class="add" @click="add">添加任务</button>
    </header>
    <!-- 列表区域 -->
    <section class="main">
      <ul class="todo-list" v-for="(e,i) in list" :key="e.id">
        <li class="todo">
          <div class="view">
            <span class="index">{{i+1}}.</span> <label>{{e.todo}}</label>
            <button class="destroy" @click="del(e.id)"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
    <footer class="footer" v-show="list.length>0">
      <!-- 统计 -->
      <span class="todo-count">合 计:<strong> {{list.length}} </strong></span>
      <!-- 清空 -->
      <button class="clear-completed" @click="cls">
        清空任务
      </button>
    </footer>
  </section>

  <!-- 底部 -->
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
  <script>

    const app = new Vue({
      el: '#app',
      data: {
        things: '',
        list: [
          { id: 1, todo: '吃饭' },
          { id: 2, todo: '睡觉' }
        ]
      },
      methods: {
        del(id) {
          this.list = this.list.filter(e => e.id !== id)
        },
        add() {
          if (this.things.trim() == '') {
            return alert('输入项不能为空!')
          }
          this.list.unshift({
            id: +new Date(),
            todo: this.things
          })
          this.things = ''
        },
        cls() {
          this.list = []
        }
      },
    })

  </script>
</body>

</html>